Description of the Art
Over the past few years, the demand for ever cheaper and lighter weight portable electronic devices has led to a growing need to manufacture durable, lightweight, and low cost electronic circuits including high density memory chips. Solid state memory devices, typically, have read write speeds on the order of nanoseconds, however, storage capacities of only a few hundred Megabytes are typically achieved. On the other hand, mass storage devices, which usually have a rotating medium, have the capability of storing multiple Gigabytes of data; however, they have read write speeds of the order of only milliseconds.
The ability to manufacture high capacity storage systems is typically constrained by the need to utilize movable or rotating parts, which is a relatively slow process compared to electronic circuit technology. In addition, reliability is a further problem, in order to decrease the read write times the movable or rotating parts tend to be utilized at as high a speed as possible. Further, if the electronic device is used in a portable application the shock resistance of the system is also typically a limitation. Power consumption, overall weight and size, and cost also are factors that limit storage systems.
To a large extent, silicon based memory devices, over the past thirty years, have contributed to a nearly constant exponential increase in the capabilities of microelectronic devices; producing unprecedented advances in computational, telecommunication, and signal processing capabilities. In turn, this increase in complexity has driven a corresponding decrease in the feature size of integrated circuit devices, which has typically followed “Moore's Law.” However, the continued decrease in feature size of integrated circuits, into the nanometer regime, has become increasingly more difficult, and may be approaching a limit, because of a combination of physical and economic reasons. Generally, silicon based memory devices involve complex architectures utilizing many layers. Each of these layers must be deposited and defined to produce the desired structure for that layer, thus each layer contributes to a higher cost for the semiconductor device. In addition, such complex architectures, typically, result in a reduction in the number of logic cells per unit area of the semiconductor substrate, leading to a reduction in the data storage density for a given chip size.
It is well recognized in the field of data storage that it is desirable to increase the storage density and reduce the cost of information stored in the storage device. This is generally true for all types of information storage devices, such as magnetic hard drives, optical drives, random access memory devices, and other information storage systems. As noted above it becomes increasingly difficult to squeeze more information into the storage devices.
If these problems persist, the continued growth, seen over the past several decades, in cheaper, higher speed, higher density, and lower power storage devices used in electronic devices will be impractical.